Nitric oxide and biopterin in depression and stress

Depression has been hypothesized to be related to the reduced biosynthesis of neurotransmitters such as serotonin, noradrenalin and dopamine. Much pas t research has also been devoted to dysregulation of the hypothalamic-pitui tary-adrenal (HPA) axis in depression. The present article reviews the evid ence linking tetrahydrobiopterin, a co-factor in the biosynthesis of neurot ransmitters, and nitric oxide, an apparent neuroendocrine modulator of the HPA axis, to the immune system and to neuronal control within affective dis order and stress. On the basis of this review, it is suggested that future psychoneuroimmunological research should more fully explore the possible ro le of tetrahydrobiopterin and nitric oxide in depressive disorders. (C) 199 9 Elsevier Science Ireland Ltd. All rights reserved.